Method of finishing heads of set screws and other articles



G. A. MOORE Sept. 8, 1931.

METHOD OF FINISHING HEADS OF SET SCREWS AND OTHER ARTICLES Filed Feb. 3, 1930 Patented Sept. 8, 1931 UNITED STATES trait PATENT OFFIE GEORGE A. MOORE, OF BOSTON, MASSACHUSETTS Application filed February 3, 1930. Serial No. 425,430.

' This invention relates to the obliteration of the teat which is left on the end face of the wrench-engaging head of a set screw made by an automatic screw machine. Such machine in converting a rod into set screws leaves a teat on the end face of each screw, as is well known.

Usually the teat is removed by a grinding operation, which is necessarily slow and therefore relatively expensive.

The object of the invention is to provide an improved method of obliterating the teat, without removing the metal thereof.

Of the accompanying drawings forming a part of this specification,--

Figure 1 is a side view of a screw-head finishing machine adapted to practice the invention, the swaging die and its carrier being retracted.

Figure 2 is a section on line 2-2 of Figure 1, and a plan view of parts below said line. V

Figure 8 isa section on line 3-3 of Figure 1.

Figure 4 is a section on line 44 of Figure 1.

Figure 5is a view similar to a portion of Figure 1, showingthe swaging die and its carrier projected to cause the die to act on a screw-head.

Figure 6 is a section on line 66 of Figure 1, and a side View of parts at the right of said line.

Figure 7 is a view similar to Figure 6, showing a different position of the diskand carrier shown by Figure 6. 1

Figure 8 shows in prespective and separated from each other the bell-crank lever and the fixed support on which it is fulcrumed, as otherwise shown by Figures 1 and 6.

Figure 9 shows in perspective a headed set screw, conditioned as it leaves the machine which makes it. 7

Figure 10 is a view similar to Figure 9, showing the finished screw.

Figure 11 is a side view of the finished screw.

The same reference characters indicate the same parts in all of the figures.

12 (Figure 9) designates a set screw including a wrench-engaging head, from the end face of which a teat 13 projects when the screw leaves the machine whereby it is made, said teat being a reduced part of a rod convcrted by the machine intoa plurality of screws.

In carrying out my invention I obliterate the teat by upsetting it and distributing its material on the end face of the head, and about the center thereof, as indicated by Figures 10 and 11 without removing said material, the outer surface 13a of the upset head being flush with the previously formed major portion of the head surrounding the teat, as shown by Figure 9. Usually the end face of the finished screw is somewhat convex, as shown by Figure 11.

The illustrated machine comprises a swaging die 14;, having a preferably concave acting face 15, mechanism for longitudinally reciprocating said die in a predetermined path, and holding means adapted to support a screw 12 in alinement with the path of the die, with the end face and teat exposed, so that the die acts to upset the teat and distribute the material thereof.

The die-reciprocating mechanism includes a cylindrical elongated die carrier 16, fixed to the die and guided therewith in a. predetermined path by fixed bearings 17 and 17a, in which the carrier is rotatable about its longitudinal axis, a spring 18 interposed between the bearing 17 and a shoulder 19 on the carrier and adapted to yieldingly project the carrier and thereby cause an upsetting action of the die on the teat, means for rotating the carrier, and means actuated by the rotation of the carrier to alternately retract and release it, the rotation of the carrier tensioning the spring 18, and the release permitting the spring to yieldingly project the carrier and cause the die to partly project the carrier, repetitions of the projection causing a progressive upsetting of the teat.

The rotation of the carrier is caused, by a belt 20 running on a pulley 21, fixed to the carrier. The means actuated by the rotation of the carrier is embodied in lugs 22 and 23, fixed respectively to the bearing 17 a and to the pulley 21, said lugs having vertical and inclined faces, as shown by Figures 1 and 5. When the die is fully projected, said lugs are arranged, as shown by Figure 5. The die carrier is rotated in the direction required to cause the inclined face of the lug 23 to first ride on the inclined face of the lug 22, as indicated by Figure 1, thus causing the retraction of the carrier. l/Vhen the lug 23 passes from the lug 22, the spring 18 is permitted to project the carrier, as indicated by Figure 5. The carrier is therefore alternately retracted positively and released and projected yieldingly.

The screws may be held during the teat obliterating operation by rotary turret 25, Whose axis is arranged at right angles with the path of the die, said turret having a plurality of radially arranged spaced apart screw-supporting sockets 26, which are preferably bushings inserted removably in recesses in the turret, so that sockets adapted to hold screws of different sizes may be used interchangeably.

The turret is rotated step by step to locate its sockets successively in the path of the die 14, by mechanism including a turret shaft 27, fixed to the turret and journaled in fixed bearings 28 and 28a, and stop means adapted to temporarily confine the turret after each partial rotation therof in position to maintain the screw head in the path of the die for a predetermined period.

The turret is arranged so that screws may be inserted by an attendant, (or auton1atically if desired), in a socket at one side of the axis, and discharged by gravity from a socket at the opposite side.

The turret-rotating mechanism includes a turret-operating shaft 30, parallel with the turret shaft 27 and journaled in a fixed bearing 31, and continuously driven by a belt 32, running on a pulley 33, fixed to the oper ating shaft, and torque-transmitting connections between the shafts 27 and 30 organized to alternately rotate and arrest the turret shaft.

Said connections include a disk 35, fixed to the operating shaft 30, and provided with an ear 36 and a stud 37 fixed thereto, and a Geneva gear 38, fixed to the turret shaft 27. The parts 35, 37 and 38 constitute a Geneva movement, the operation of which is so well known that a description thereof appears unnecessary.

adapted to bear on a side of the disk 40 and displaceable outwardly therefrom by the cam 41. The arrangement is such that when the arm 47 is displaced by the cam, the lifting arm 44 is raised to hold the die carrier in a retracted position and prevent the operation of the die. When the cam 41 passes from the arm 47, said arm contacts with the disk 40 and the lifting arm 44 permits the described reciprocation of the die carrier and the normal operation of the die.

It will be seen that my invention includes a method of finishing the cut off end of a screw machine product, said end including a teat projecting from and surrounded by an end zone previously finished by the screw machine, said method consistingin supporting said product against upsetting force exerted on the teat, and exerting. such force while the product is supported, and thereby converting the metal of the teat into a finished central zone flush with and merging'into said previously finished zone, none of the metal being removed. In other words, said method consists in displacing the material of the teat by percussion endwise thereof, and radially outward, to mushroom the teat and convert it into a central zone substantially continuous with the previously finished zone.

It is obvious that this method may be employed in finishing screw machine products other than set screws, such as cap screws, shoulder screws, blind nuts, and studs.

I claim:

The method of finishing the cut-off incomplete end or head of. a screw-machine product, said end including a previously finished zone and a teat projecting from the center of said zone and interrupting the continuity thereof, said method consisting in displacing thematerial of the teat by percussion endwise thereof, and radially outward, to mushroom the teat and convert it into a central zone, substantially continuous with: the previously finished zone.

In testimony whereof I have aflixed my signature.

GEORGE A. MOORE. 

